1. Field of the Invention
This invention relates generally to semiconductor manufacturing, and, more particularly, to a method and apparatus for performing a proactive processing line control to improve line balancing in semiconductor manufacturing.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today""s manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and therefore, require a number of inputs that are generally fine-tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing areas or locations that contain different control schemes.
Generally, a set of processing steps is performed on a group of semiconductor wafers, sometimes referred to as a lot, using a semiconductor manufacturing tool called an exposure tool or a stepper. Typically, an etch process is then performed on the semiconductor wafers to shape objects on the semiconductor wafer, such as polysilicon lines, each of which may function as a gate electrode for a transistor. The manufacturing tools communicate with a manufacturing framework or a network of processing modules. Each manufacturing tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface to which a manufacturing network is connected, thereby facilitating communications between the manufacturing tool and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script, which can be a software program that automatically retrieves the data needed to execute a manufacturing process.
FIG. 1 illustrates a typical semiconductor wafer 105. The wafer 105 typically includes a plurality of individual semiconductor die 155 arranged in a grid 150. Photolithography steps are typically performed by a stepper on approximately one to four die locations at a time, depending on the specific photomask employed. Photolithography steps are generally performed to form patterned layers of photoresist above one or more process layers that are to be patterned. The patterned photoresist layer can be used as a mask during etching processes, wet or dry, performed on the underlying layer or layers of material, e.g., a layer of polysilicon, metal or insulating material, to transfer the desired pattern to the underlying layer. The patterned layer of photoresist is comprised of a plurality of features, e.g., line-type features or opening-type features that are to be replicated in an underlying process layer.
Generally, a system for scheduling the manufacturing processes of semiconductor wafers is employed in semiconductor device manufacturing environments. Often, marketing factors, such as demand for a semiconductor device with a particular speed of operation, drive the processing operation in a manufacturing environment (e.g. a semiconductor device manufacturing fab). The capacity of a manufacturing environment, availability of processing tools, and other factors determine the scheduling of processing of semiconductor wafers. Generally, each type of processing capacity (e.g., the fab""s capacity to perform a particular type of etch process) is considered separately when scheduling processing of semiconductor wafers.
A process control system generally considers individual process capacity to schedule requested processing tasks. For example, a request may be made to process semiconductor wafers to produce a certain number of devices containing 2.5 micron connectivity lines, within a certain time. The process control system then allocates various processing tools in a fab to accommodate the request based upon tool capacity. The process control system generally analyzes individual operations and provides direction to efficiently operate individual processes. Dispatching of processing tasks is generally based upon requests for processing certain type of devices and the processing capacity of the manufacturing environment. This method can cause inefficiencies in processing semiconductor wafers, resulting in lost fab time, and slower rates in completing a variety of semiconductor devices.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
In one embodiment of the present invention, a method is provided for performing a proactive dispatch to improve line balancing. At least one request for processing at least one semiconductor wafer is received. A line-balancing analysis based upon the request is performed. At least one semiconductor wafer based upon the line-balancing analysis is processed.
In another embodiment of the present invention, a system is provided for performing a proactive dispatch to improve line balancing. The system of the present invention comprises: a simulation environment capable of simulating at least one process operation performed on a semiconductor wafer and generating simulation data; a process scheduling model in communication with the simulation environment, the process scheduling model capable of performing a process scheduling function based upon at least one of the simulation data and a metrology data, to control the process operation; and a process control in communication with the process scheduling model, the process control capable of performing a line balancing function to control a processing of at least one semiconductor wafer based upon the process scheduling function.